When assembling components on a circuit board, it is most convenient if the components are mounted on the board while their terminal members are soldered in place. For instance, a conventional surface-mount edge connector as shown in FIG. 1 should first be secured to the surface of the circuit board while all terminal members are soldered to the appropriate traces on the surface of the circuit board.
Various types of boardlocks have been developed for the above-described purpose. For example, the connector may be riveted to the circuit board prior to soldering. Riveting is both durable and permanent, and it has other advantages which extend beyond the manufacturing process. For instance, after manufacturing, the circuit board will inevitably absorb shocks and vibrations which would otherwise fracture the terminal member solder joints. Instead, the rivets absorb the shock. Unfortunately, specialized tools and procedures are required to insert the rivets during the manufacturing process. In addition, the connector housing must have protuberances by which the rivets may clasp the connector. For this purpose, mounting-ears are generally provided around the periphery of the connector housing. However, the mounting-ears consume valuable space on the surface of the circuit board.
Other well-known devices such as weldments and adhesives do nothing to solve the above-described problems. Fortunately, recent modifications and improvements have been more availing.
For example, in U.S. Pat. No. 4,842,552 issued to Frantz, a tolerance forgiving boardlock is disclosed. The Frantz '552 boardlock is employed in a manner similar to a rivet. However, installation is much easier. As shown in FIG. 2, each boardlock comprises a crown formed with a plurality of resilient legs extending downward along a longitudinal axis. The legs are formed with elbows along their length, i.e., the legs diverge, and then converge toward a common axis. The boardlocks are inserted through mounting-ears extending from the connector housing. During insertion, the resilient legs constrict until the elbows have cleared the circuit board. Once clear, the legs deflect radially outward. The elbows engage the underside of the circuit board to provide a secure resistance fit. The Frantz '552 boardlock eliminates the need for specialized insertion tools.
Moreover, the resilient legs are more accommodating of inexact manufacturing tolerances. Unfortunately, the interference fit of the Frantz '552 boardlock requires significant insertion force. This hinders the assembly process. Furthermore, the Frantz '552 boardlock does not protect the solder connections as would a rivet. When a substantial force is applied to the connector, it will be absorbed by the solder contacts as well as the boardlocks.
U.S. Pat. No. 4,717,219 to Frantz, et al. proposes a partial solution. A deformable boardlock is disclosed for insertion on the tip of a specialized insertion tool. The boardlock is inserted until its flanged head limits further insertion. At this point, the insertion tool bears on a concave indentation at the tip of the boardlock. Further insertion of the tool flattens the indentation, which in turn causes a flaring of the boardlock around the tip. As a result, the circuit board and connector tab became sandwiched between the flanged head and flared tip of the boardlock. Hence, the Frantz, et al. '219 boardlock provides a more permanent, durable and tolerance forgiving anchor.
Even though Frantz, et al. '219 provides an excellent anchor, the improvement complicates the manufacturing process. A customized insertion tool is necessary for assembly. Moreover, the connector must be held in alignment with the circuit board while the boardlocks are installed, and mounting-ears are required around the connector housing.
It would be greatly advantageous to eliminate the above-described drawbacks in an anchoring mechanism with a binding force equivalent to the Frantz, et al. '219 boardlock.